To improve the thermodynamic properties of internal combustion engines, valve drives, in which the working cycle can be influenced in order to make it possible to vary, for example, as a function of speed, the opening times or the stroke of the gas exchange valves, are known.
A valve drive of the initially mentioned type is already known from EP 1 608 849 B1. In the known valve drive, for axial movement of the cam support, the devices comprise two worm drives with mirror-image curved pathways, which are arranged on the opposing front ends of the cam support and comprise a right-twist or a left-twist helical groove, as well as with two final control elements that are mounted at the axial distance in the cylinder head housing of the internal combustion engine, elements which in each case comprise an engaging element that is designed as a carrier pin, which can be engaged with the groove of the adjacent curved pathway by activating the final control element, in order to move the cam support to the right or the left.
To improve the possibilities for influencing the working cycle of the valve drive, it would be desirable to expand the cam groups or cam profile groups of the cam support by another cam or another cam profile with another contour. This necessitates, however, moving the cam support back and forth between three different shift positions. A scaling-up of the number of final control elements or actuators in the cylinder head or a widening of a section of the cam support that is provided with the curved pathways is undesirable, however, not only because of the larger axial installation space required for this purpose but also because of the higher assembly cost.
Based on this, the object of the invention is to improve a valve drive of the initially mentioned type to the extent that the axial installation space required for the final control element or the curved pathways and the number of parts to be mounted can be reduced.